In closed environments, such as those found in submarines and spacecraft, the control of microbial agents has always been a primary concern. This concern is particularly significant in water treatment systems that remove various inorganic substances, ions, organic substances and microorganisms from water so as to render the water ultrapure or potable. The effectiveness of such systems is dependent upon not only the ability of the system to consistently remove contaminants in the water that approach or exceed "acceptable levels" but also the ability of the system not to become contaminated with microbial agents in the process.
The use of ion exchange resins with considerable variations in acid and base strength in water treatment systems is known. Such resin dependent systems generally operate under moderate temperature and pressure conditions where the resins employed are not all stable at elevated temperatures. In particular, strong and weak base anionic resins typically degrade at temperatures approaching 60.degree. C. Strong and weak acid cationic resins are more thermally stable and typically degrade at temperatures approaching 121.degree. C. to 149.degree. C. Although a few weak base anionic resins have been identified as stable at elevated temperatures these resins are not the most viable candidates for use in water treatment systems where they do not demonstrate a high capacity for anions.
The general type of water treatment system utilizing resins is dependent upon the feed water source (i.e., pretreated or untreated water supplies). Such systems typically employ multiple ion exchange resin beds, with each bed targeting specific water contaminants. In multiple bed systems that process untreated water select "polishing" resin beds are typically located after a two or three bed treatment configuration for removal of trace amounts of contaminants that may still be present in the effluent from the upstream resin beds. In multiple bed systems that process treated water such "polishing" resin beds would define or make up the system.
It has been observed in water treatment systems that utilize ion exchange resin beds or activated carbon beds that bacteria tends to collect and grow within the beds. Prior art techniques aimed towards inhibiting the growth of bacteria within ion exchange resin beds involve the addition of bacteriostatic chemicals like iodine and iodine compounds to the beds or periodic back flushing of the beds. Yet such control or inhibition techniques result in high resupply weight and/or volume penalties in submarine and spacecraft applications.
It is therefore an object of the present invention to provide thermally sterilizable polishing agents that enable the control and maintenance of a microbial free environment.
It is a further object of the present invention to provide thermally sterilizable polishing agents that serve to obviate the need for chemical or mechanical microbial control or inhibition techniques.
It is still a further object of the present invention to provide a process for removing contaminates from an aqueous solution that utilizes such thermally sterilizable polishing agents.
It is yet a further object to provide a system for removing contaminants from an aqueous solution that utilizes such thermally sterilizable polishing agents.